Surgical tools designed for mechanical cutting of tissue have been used for a number of years. These types of tools typically include a powered handpiece and a cutting tool which is secured in the distal end of the handpiece. The tool has an inner drive member including a hub drivingly engaged with an output shaft associated with a motor of the handpiece, and a drive shaft fixed to the hub which defines a cutting implement or head at a distal end thereof. An outer cannulated housing element is disposed about the drive shaft of the inner drive member and defines a cutting window thereon which cooperates with the moving cutting head to manipulate targeted patient tissue positioned adjacent the window.
Electrosurgical tools have also been available for many years, which tools employ electrical energy to treat targeted patient tissue in various ways. For example, electrocauterization is utilized to seal off and close blood vessels during surgery to prevent blood loss. In addition, ablation is utilized to vaporize or remove tissue using electrical energy. Electrosurgical probes are typically designed to perform both of these functions, depending upon the level of power supplied thereto. Further, monopolar and bipolar electrosurgical tools are conventional wherein monopolar tools direct electric current from an active electrode defined on the tool through the patient's body to a return electrode, which return electrode is typically defined by a grounding pad attached to the patient. Bipolar tools, on the other hand, include both an active and return electrode, wherein the current is directed from the active electrode to the return electrode through the contacted tissue.
Tools which are capable of both of the above functions are known. For example, U.S. Pat. No. 4,815,462 discloses a lipectomy device having a housing which mounts thereon an outer conduit, and a rotatable cutting blade disposed within the conduit. The rotatable cutting blade includes a distal end or tip which is interconnected to an electrical circuit which heats the tip so that same can be used for electrocoagulation of blood vessels.
U.S. Pat. No. 5,941,876 discloses a further electrosurgical rotating cutting device. This device incorporates an outer cannula structure in which a rotating cutting element is disposed. The outer cannula structure includes a commutator which effectively delivers electrical energy to the rotating cutter so that same serves as an active, energy delivering electrode. The device can be used as a monopolar instrument, for example by using the rotating cutter as an active electrode, and a remote grounding pad as the return electrode. Alternatively, the device can be used in a bipolar manner, by using an exposed portion of a sheath, which forms part of the outer cannula structure, as a return electrode.
One disadvantage of the above tools is that, since the rotating blade tip is utilized as the active, energy-delivering electrode, the surface area of the active electrode defined by the rotating blade tip varies, which can create inconsistent energy delivery and thus inconsistent performance.
U.S. Pat. No. 6,193,715 discloses an adapter unit for retrofitting on an existing surgical tool, such as a mechanical cutting implement, to convert same to a bipolar electrosurgical device. The device may also be used to convert a monopolar surgical device to a bipolar surgical device. The adapter unit includes a tubular sheath or conduit having a mounting block at one end of the sheath which is connected to a power source. The mounting block defines a pair of electrical signal connector pins. When the mechanical cutting device is positioned inside the adapter unit, one of these pins is in electrical connection with a conductive portion of the cutting device, and the other of the pins is electrically connected to a conductive intermediate layer of the sheath, which effectively converts the cutting device to a bipolar electrosurgical instrument. This adapter device, however, requires that an additional housing (i.e. the sheath) be placed over the existing housing of the cutting device, which significantly increases the overall size of the device, which in turn requires that a larger entry port be made in the patient.
In order to obviate or at least minimize the above disadvantages of known arrangements, the surgical tool arrangement according to the invention provides an integrated tool which detachably mounts to a powered handpiece and is of minimal overall size, does not utilize a rotating component for energy delivery to targeted tissue, and includes an active electrode provided on a stationary housing with a small surface area that enables improved energy delivery at the mechanical cutting interface. More specifically, the surgical tool arrangement includes an outer housing element including a hub arrangement which mounts to a coupling arrangement of the handpiece, and an elongated cannula or sheath fixed to the housing and in which a movable cutting element is disposed. The cannula defines an opening or window at a distal end thereof so as to expose the cutting head of the cutting element. Electrical energy is provided to an electrode arrangement provided on the cannula, and an electrode is defined immediately adjacent the window at the cutting interface. The electrical energy is returned via a grounding pad or alternatively via a conductive portion of the cannula.
Because the instant invention does not utilize the moving cutting element as an energy delivering electrode, the energy delivery at the cutting interface is consistent, thus resulting in more consistent tool performance. Further, since the moving cutting element is not utilized as an active electrode, there is no requirement to electrically isolate the mechanical cutting element from the outer housing element.
Further, the instant invention incorporates an electrical coupling between the handpiece and the integrated tool, which coupling provides electrical energy to the electrode arrangement of the integrated tool via the handpiece, thereby eliminating the need for a separate power cable.
Still further, the invention relates to a universal handpiece which is capable of accepting and operating a number of different surgical tools or instruments, each having one or multiple functions.
Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. The words “forwardly” and “distally” will refer to the direction toward the end of the arrangement which is closest to the patient, and the words “rearwardly” and “proximally” will refer to the direction away from the end of the arrangement which is furthest from the patient. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.